Left Diastolic Function in Critically Ill Mechanically Ventilated Patients

Abstract

Left ventricular (LV) diastolic dysfunction is a clinical entity that remains poorly understood and identified in the intensive care unit (ICU) setting. In general, it is a syndrome defined by the presence of symptoms of congestive heart failure without sign of reduced LV systolic dysfunction [1]. Distinguishing diastolic heart failure from systolic heart failure is important because of differences in treatment and prognosis, even if the two entities often coexist, and some authors have proposed the hypothesis that diastolic LV dysfunction is essentially a precursor of systolic failure [2]. Diastolic dysfunction has multiple causes and is associated with multiple disorders, including impaired relaxation (common in ischemia and during systemic inflammatory states), impaired peak LV filling (with inadequate transmitral pressure gradient due to raised LV pressure or inability to generate negative LV pressure), stiffness of the left ventricle (fibrosis and hypertrophy), and constriction (pericardial or compression from dilated right ventricle). Diastolic LV dysfunction is common in the ICU but often unrecognized. Identification and determination of its severity may be useful to optimize circulatory support in critically ill patients. From this point of view, echocardiography is one of the most powerful diagnostic and monitoring tools available to the modern intensivist, providing the means to diagnose cardiac systolic or diastolic dysfunction, its underlying cause, and to suggest therapeutic interventions [3].